1. Field of the Invention
The present invention relates to a plastic fastener that is used for fastening panels in a state of mutual contact or for fastening parts to panels.
2. Description of the Prior Art
Plastic fasteners are extensively used for affixing components in cars, electrical appliances and the like. Their good manufacturability, ease of use and other such qualities have made plastic fasteners an essential element for attaching automobile components.
The shape and form of such plastic fasteners depends on how and where they are used. Fasteners used for attaching panels together or attaching parts to panels usually consist of a main post member for insertion into through holes formed in the panels or in the panel and component, barbed retainer pieces provided at the end of the post to stop the post being withdrawn, and a contact plate member that is provided at the top end of the post and acts in concert with the retainer pieces to clamp the panels together, or a component to a panel, therebetween, and the fastening usually can be accomplished by the insertion of the post through the holes.
First and foremost, a fastener has to be able to fulfill its function of fastening. However, to enable parts to be replaced, for inspection and maintenance purposes, and for disassembly for disposal purposes and the like, it is also important to be able to unfasten fasteners. Conventional fasteners have responded to this need in various ways. One way is by making the post hollow and inserting a pin into the hollow space from the end of the post to thereby expand the end and cause the retainers to lock into engagement, whereby the fastener can be unlocked by removing the pin; in another arrangement, the fastener is unfastened by rotating the post in position in the holes to align the retainers with a slot formed in the holes, thereby allowing the post to be withdrawn.
However, whether it is a matter of withdrawing a pin or of rotating a member, in each case these are operations that have to be directly applied to remove the fastener, and under actual work conditions such operations are difficult to do. For example, there has to be enough space to withdraw a pin, and turning a post involves the use of tools and it is necessary to ensure that there is enough space for the task.